Saturation Boiling Critical Heat Flux of PF 5060 Dielectric Liquid on Microporous Copper Surfaces

Abstract

Pool boiling experiments are performed to investigate potential enhancement of critical heat flux (CHF) of PF5060 dielectric liquid on microporous copper (MPC) surfaces and the effect of surface inclination angle. The morphology and microstructure of the MPC surfaces change with thickness. The experiments tested seven 10 أ— 10 mm MPC surfaces with thicknesses from 80 to 230 خ¼m at inclination angles of 0 deg (upward facing), 60 deg, 90 deg (vertical), 120 deg, 150 deg, 160 deg, 170 deg, and 180 deg (downward facing). CHF increases as the thickness of the surface increases and/or the inclination angle decreases. The values in the upward facing orientation are 36–59% higher than on smooth Cu. For all surfaces, CHF values in the downward facing orientation are approximately 28% of those in the upward facing orientation. A developed CHF correlation, similar to those of Zuber and Kutateladze, accounts for the effects of inclination angle and thickness of the MPC surfaces. It is in good agreement with experimental data to within آ±8%. Still photographs of nucleate boiling on the MPC surfaces at different inclinations help the interpretation of the experimental results.